Question

我有一个数据库，如图所示。我们以下面的数据为例：

WORKORDER 表：

WONUM (PK)  |  WORKTYPE  | STATUS |  DESCRIPTION
1234           URGENT      OPEN      Inv. work X.

FAILUREREPORT 表：

FAILUREREPORTID (PK) | WONUM | FAILURECODE | ASSETNUM  | TYPE   
5678                   1234    SYMPT1347     DT-JA-123   Problem
5679                   1234    WA4521        DT-JA-123   Cause
5680                   1234    SOL1672       DT-JA-123   Solution

FAILURECODE 表：

FAILURECODEID (PK) | FAILURECODE | DESCRIPTION
345                  SYMPT1347     Symptom X.
346                  WA4521        Cause Y.
347                  SOL1672       Solution Z.

我有以下查询，它完成了一半的工作：

SELECT F.WONUM, W.DESCRIPTION AS WO_DESC, W.STATUS, F.ASSETNUM, F.TYPE, C.DESCRIPTION AS FCODE_DESC
FROM WORKORDER W
INNER JOIN FAILUREREPORT F ON F.WONUM = W.WONUM
INNER JOIN FAILURECODE C ON F.FAILURECODE = C.FAILURECODE
WHERE W.WORKTYPE = 'URGENT' AND W.STATUS <> 'CANCELLED'
ORDER BY F.WONUM ASC, F.TYPE ASC

它返回：

WONUM | WO_DESC              | STATUS | ASSETNUM | TYPE    | FCODE_DESC
1234    Inv. work X.           OPEN     DT-JA-123  PROBLEM   Symptom X.
1234    Inv. work X.           OPEN     DT-JA-123  CAUSE     Cause Y.
1234    Inv. work X.           OPEN     DT-JA-123  SOLUTION  Solution Z.

但是，我希望在一行中列出症状，原因和解决方案，而不是3行，如下所示：

WONUM | WO_DESC     | STATUS | ASSETNUM | PROBLEM   | CAUSE  |  SOLUTION
1234    Inv. work X.  OPEN     DT-JA-123  Symptom X.  Cause Y.  Solution Z.

如果有可能，如何使用pivot功能将行转换为列？我也对任何能够产生预期结果的其他解决方案持开放态度。我操作的数据库是Oracle DB，而我的游乐场/测试环境是MySQL。我知道不能在MySQL中使用数据透视表，但是通过聚合和分组可以解决这个问题。

Answer 1

您需要一个案例陈述。试试这个

SELECT F.WONUM, 
       W.DESCRIPTION AS WO_DESC, 
       W.STATUS, 
       F.ASSETNUM, 
       MIN (CASE WHEN TYPE = 'PROBLEM' THEN C.DESCRIPTION END) AS PROBLEM,
       MIN (CASE WHEN TYPE = 'CAUSE' THEN C.DESCRIPTION END) AS CAUSE,
       MIN (CASE WHEN TYPE = 'SOLUTION' THEN C.DESCRIPTION END) AS SOLUTION
FROM WORKORDER W
INNER JOIN FAILUREREPORT F ON F.WONUM = W.WONUM
INNER JOIN FAILURECODE C ON F.FAILURECODE = C.FAILURECODE
WHERE W.WORKTYPE = 'URGENT' 
AND W.STATUS <> 'CANCELLED'
GROUP BY F.WONUM, 
         W.DESCRIPTION, 
         W.STATUS, 
         F.ASSETNUM
ORDER BY F.WONUM ASC

Answer 2

使用子查询：

SELECT w.wonum, w.description AS wo_desc, w.status,
  (SELECT assetnum FROM FAILUREREPORT WHERE wonum = w.wonum LIMIT 1) assetnum,
  (SELECT description
   FROM FAILUREREPORT JOIN FAILURECODE USING(failurecode)
   WHERE type = 'PROBLEM' AND wonum = w.wonum) problem,       
  (SELECT description
   FROM FAILUREREPORT JOIN FAILURECODE USING(failurecode)
   WHERE type = 'CAUSE' AND wonum = w.wonum) cause,       
  (SELECT description
   FROM FAILUREREPORT JOIN FAILURECODE USING(failurecode)
   WHERE type = 'SOLUTION' AND wonum = w.wonum) solution
FROM WORKORDER w
WHERE w.worktype = 'URGENT' AND w.status <> 'CANCELLED'
ORDER BY wonum ASC

SQL将行信息合并/转换为列

2 个答案: